What does a verbs tense tell you?

Verb tenses tell us how an action relates to the flow of time. There are three main verb tenses in English: present, past and future. The present, past and future tenses are divided into four aspects: the simple, progressive, perfect and perfect progressive. These are called helping, or auxiliary verbs. The tense of a verb can also tell us things like whether the action is habitual, ongoing, or completed. This is called the aspect of the verb, which is part of tense.

As the boys sleep, military airplanes battle fiercely above the island. none of the boys sees the explosions and flashes in the clouds because the twins sam and eric, who were supposed to watch the signal fire, have fallen asleep. during the battle, a parachutist drifts down from the sky onto the island, dead.